Method and apparatus for network synchronization in satellite communication system

Abstract

A method and an apparatus for network synchronization in a satellite communication system is provided. a satellite station receives a superframe start timing (SST) and an initial counter value from a center station, and receives traffic information sent from a terminal station at a time determined based on the SST. Then, the satellite station generates a compensation value for the SST upon receiving the traffic information, and corrects the SST in accordance with the compensation value.

What is claimed is: 
     
       1. A method for network synchronization in a satellite communication system, the method comprising:
 receiving, by a satellite station, a superframe start timing (SST) and an initial counter value from a center station; 
 receiving, by the satellite station, traffic information sent from a terminal station at a time determined based on the SST; and 
 generating, by the satellite station, a compensation value for the SST upon receiving the traffic information, and correcting the SST in accordance with the compensation value. 
 
     
     
       2. The method of  claim 1 , wherein the correcting of the SST includes obtaining the compensation value by using a timing offset corresponding to the traffic information and a preset half guard time (HGT). 
     
     
       3. The method of  claim 1 , wherein the correcting of the SST includes:
 estimating a timing offset corresponding to the traffic information; 
 obtaining the compensation value by subtracting a preset half guard time (HGT) from an estimated timing offset; and 
 correcting the SST in accordance with the compensation value. 
 
     
     
       4. The method of  claim 3 , wherein the correcting of the SST in accordance with the compensation value includes obtaining a corrected SST by adding the compensation value and SFD tick  to the SST,
 wherein the SFD tick  is a superframe duration clock tick. 
 
     
     
       5. The method of  claim 1 , further comprising sending, by the satellite station, the corrected SST to the center station. 
     
     
       6. The method of  claim 1 , further comprising receiving, by the satellite station, traffic information from the terminal station in accordance with a value counted from the initial counter value and the corrected SST. 
     
     
       7. The method of  claim 1 , wherein the satellite station periodically sets an initial clock counter value. 
     
     
       8. The method of  claim 7 , wherein a stamping cycle is determined in accordance with a specification of a data processing equipment (DPE) clock of the center station, and the initial clock counter value is periodically set in accordance with the stamping cycle. 
     
     
       9. The method of  claim 1 , wherein the traffic information is sent from the terminal station at a transmission time determined by using timing error information, which the terminal station receives from the center station, and the SST. 
     
     
       10. The method of  claim 1 , wherein the satellite system is a multi frequency-time division multiple access (TDMA)-based very small aperture terminal (VSAT) satellite communication system. 
     
     
       11. A satellite apparatus in a satellite communication system, comprising:
 a network interface device; and 
 a processor, 
 wherein the processor is configured to perform: 
 an operation of receiving a superframe start timing (SST) and an initial counter value from a center station through the network interface device; 
 an operation of receiving traffic information sent from a terminal station at a time determined based on the SST through the network interface device; and 
 an operation of generating a compensation value for the SST upon receiving the traffic information, and correcting the SST in accordance with the compensation value. 
 
     
     
       12. The satellite apparatus of  claim 11 , wherein, in performing the operation of correcting the SST, the processor is configured to obtain the compensation value by using a timing offset corresponding to the traffic information and a preset half guard time (HGT). 
     
     
       13. The satellite apparatus of  claim 11 , wherein, in performing the operation of correcting the SST, the processor is configured to perform:
 an operation of estimating a timing offset corresponding to the traffic information; 
 an operation of obtaining the compensation value by subtracting a preset HGT from an estimated timing offset; and 
 an operation of correcting the SST in accordance with the compensation value. 
 
     
     
       14. The satellite apparatus of  claim 13 , wherein a corrected SST is obtained by adding the compensation value and SFD tick  to the SST,
 wherein the SFD tick  is a superframe duration clock tick. 
 
     
     
       15. The satellite apparatus of  claim 11 , wherein the processor is configured to additionally perform:
 an operation of sending the corrected SST to the center station through the network interface device; and 
 an operation of receiving traffic information from the terminal station in accordance with a value counted from the initial counter value and the corrected SST.